Questions 21 to 24 are based on the following passage:Right now in schools across the country children are busy selling Pepsi-Cola in the name of education. They are part of Pepsi's “Learn and Earn Project”-an annual competition set up by Pepsi that encourages students to sell the soft drink at parties, basketball games and other school functions.Then, each spring, the students write up their Pepsi-selling success stories for a chance at national prizes: shares of stock in the Pepsi-Cola Company.According to materials the company sends the teachers, the project declares “helpstrengthen students' broad understanding of business, particularly its merchandising aspect. ”Whether it fulfills this objective or not, it does succeed in selling Pepsi.The “Learn and Earn Project” is just one example of the hundreds of ways food companies (as well as other types of corporations, public utilities and trade associations) promote their products in schools. Particularly in the fields of nutrition and home economics, companies send numerous “teaching aids”: highly professional films, shiny workbooks and pamphlets, all available to teachers at well below commercial rates or free.For example, the Savannah Sugar Refining Corp. puts out a book for students called “Sugar Through the Ages” which includes statements such as “Scientists have found that generous amounts of sugar are a valuable part of well-balanced diets for growing children.” By far the largest supplier of nutrition-education materials to schools is the National Dairy Council, which provides all sorts of pamphlets addressing questions ranging from “How am I doing socially?” to “How am I doing physically?”Woven throughout these materials are subtle references to dairy products, daily calcium requirements, etc. Drink milk, the message seems to be, and you too can be popular.But nutrition and home economics are not the only areas where corporations have found a lucrative form of advertising.21.What is NOT true of Pepsi's “Learn and Earn Project”?A.It is carried out every year.B.Students may gain a better understanding of business administration.C.Students selling Pepsi-Cola successfully will become stockholders in the company.D.The Pepsi Company gains much profit from it.22.In citing the statement from the book “Sugar Through the Ages” (Para. 6), the author's purpose is______.A.to expose the true motives of those corporations in providing their “teaching aids”B.to praise the Savannah Sugar Refining Corp. for its scientific point of viewC.to explain the educational function of the “teaching aids”D.to show how students and teachers can receive nutrition education more scientifically23.What is said about the educational materials supplied by the National Dairy Council?A.They strongly recommend the use of dairy products on a daily basis.B.They indirectly mention the importance of dairy products.C.They subtly deal with questions about the popularity of dairy products.D.They incorrectly report the nutritional components of dairy products.24.What is the main idea of the passage?A.Pepsi's “Learn and Earn Project” helps broaden students' understanding of business.B.Many big companies finance schools' educational projects.C.Students learn much knowledge of nutrition and home economics through their practice of business.D.Various types of corporations extend the promotion of their products to schools.